It may sound like a return to the dark ages, but using straw as a construction material is a genuine technique which has now expanded beyond the realms of ‘Grand Designs’ and self-builds, and into the commercial market.
A joint project between the University of Bath and ModCell architects has culminated in seven properties reaching the market in Bristol. Clad in brick, these homes look similar to the incumbents of the typical British street, but inside they are timber framed and walled with straw, concealed from the occupant by wooden panelling.
An estimated 3.8million tonnes of straw goes to waste in the UK every year. It is a bi-product from food production and a cheap, readily available resource. Not only this but, when laid in the correct densities, it is an extremely effective insulator.
The structural loads of the properties are taken by the timber framing, so the straw acts to insulate the property for sound and heat loss, as well as providing a sense of solidity to the external envelope.
The results? A 90% reduction in heating bills and a 20% reduction in construction costs, as against traditional masonry techniques.
As surveyors, our initial thoughts inevitably swung towards fire-risk and weather penetration, but Professor Walker of the University of Bath is confident that this is not a significant issue:
“Over the past three years of research we have looked at various aspects of the performance of straw. Two that particularly come to mind as concerns or apprehension from potential users of straw are fire-resistance and weather-resistance.
“We have conducted a number of fire tests that have demonstrated that fire resistance from straw bale construction is remarkably good and better than many contemporary forms of construction.
“In terms of durability, we have undertaken laboratory tests and undertaken monitoring of existing buildings and we have also done accelerated weather tests. The results of all these tests suggest that straw is a very durable construction solution”
With 3.8million tonnes of surplus straw, experts estimate that 500,000 new homes could be constructed; estimating that, on average, a three-bedroom house would require 7.2 tonnes of straw.
Cornwall is the location of the next project in this vein, with Leeds already containing a development of this type.
Would you live in a straw house? Is this the future, or a return to primitive methods?
Let us know your thoughts.